Add interruptor utilities

Expose wrapper functions for interrupting blocking calls, for process
and sockets.

app/src/util/process_intr.h

@@ -0,0 +1,13 @@
+#ifndef SC_PROCESS_INTR_H
+#define SC_PROCESS_INTR_H
+
+#include "common.h"
+
+#include "intr.h"
+#include "process.h"
+
+bool
+sc_process_check_success_intr(struct sc_intr *intr, sc_pid pid,
+                              const char *name);
+
+#endif